Apparatus and method for collecting soil solution samples

ABSTRACT

A system for collecting soil solution samples including a sampling device arranged to contact soil and coupled to a vacuum source, and a suction unit for automatically controlling pressure and time of operation of the vacuum source to provide suction for withdrawing solution from the soil through the sampling device and abrupt release of the vacuum at the end of a pre-defined sampling period, and a method for collecting soil solution samples including coupling a sampling device to a vacuum source, planting the sampling device in soil to be monitored, automatically controlling pressure and time of operation of the vacuum source to provide suction for withdrawing solution from the soil through said sampling device, and automatically stopping the vacuum source and abruptly releasing the vacuum at the end of a pre-defined sampling period.

FIELD OF THE INVENTION

The present invention relates to devices for collecting soil solutionsamples in general and, in particular, to a device for sampling soilsolutions, in order to optimize irrigation and fertilization.

BACKGROUND OF THE INVENTION

Over the past few decades, agricultural technology has developed byleaps and bounds. One of the most important advances in the fieldconcerns fertilizer irrigation control (fertigation). Based on real timesamples of soil solutions, this technology is geared towards improvingthe yield and quality of the final product, as well as saving water andfertilizer costs.

The goals of fertigation control are:

-   -   To improve the efficacy of water use and fertilizers.    -   To save costs.    -   To avoid mistakes in the growing process.    -   To keep the environment under control (e.g., avoid contamination        of underground reservoirs).

The existing technology is principally manual, involving simpleinstruments and a great deal of manpower. Unfortunately, the processitself is too complicated for most farmers. Thus, although the benefitsof manual real time control (RTC) of fertigation for fine-tuning thefertilization and irrigation process of various crops are commonknowledge, few farmers routinely use the technique.

In order to utilize RTC technology, farmers or crop growers manuallyextract soil solution samples adjacent the roots of the plants by meansof a syringe inserted into a soil solution extraction tube planted inthe ground adjacent the roots. Typically, extraction tubes for samplingare installed at at least two different depths in every sampling site,according to the type of plant and the typical root zone shape. Forinstance, in order to take samples at three different depths, the rootzone space is divided into three layers: one-third from the soilsurface, two-thirds from the soil surface, and at the bottom of the rootzone. An extraction tube is installed in the soil solution at eachlayer.

The sampling process begins some time after irrigation is complete, withthe delay ranging from minutes to hours, in order to carry out thesampling in optimal conditions, preferably when the soil solution stateis stable. The two parameters which have the greatest effect on thewater distribution in the irrigated soil are soil type (light, medium orheavy) and the system used in irrigation (drip, sprinkling or furrow).Vacuum suction of the solutions from the soil generally takes place overseveral hours, depending on the type of soil. The vacuum power appliedby the farmer using the syringe, time delay from end of irrigation, andthe amount of time suction is applied until sampling is completednaturally differ each time a sample is extracted. In particular, theextraction tube slowly returns to atmospheric pressure over time, whenvacuum is no longer applied, so there is no abrupt release of vacuum andthere can be no precise calculation of the volume collected or samplingtime. This is problematic, as the process results in inconsistentconditions and results. When the fine tuning of the system is moreaccurate, more significant results can be achieved.

When the sampling process is complete, the soil solution samples arecollected by the farmer from the fields and taken to a lab to beanalyzed. Alternatively, the samples can be analyzed at the site ofsampling using a field test kit. The lab results are examined by thegrower who, by following the changes in each tested parameter, such assalinity (e.c.), acidity (pH), and NPK, over time, is now capable ofmaking educated decisions about irrigation and fertilization, so as toregulate irrigation and fertilizer use more accurately and efficiently.For example, using the accumulated data, the farmer can select samplingconditions (amount of time after irrigation is complete, time span ofthe sampling and the vacuum power in the system), and fertigationparameters (water quantities and fertilization solution content).

As things stand today, the sampling process is complicated and theresults are inadequate. Farmers must be present at each sampling stationat the beginning of the process to operate the measuring equipment, andeither have to wait until the vacuum suction is complete, or must rushback immediately after its conclusion, in order to release the pressurein the soil extraction tubes so as to achieve close to controlledconditions. Because this requires extensive mental and physical activityabove and beyond the actual tending of the plants and the results areinconsistent, not many farmers use this manual technology. This holdstrue even for farmers aware of its immense economic and environmentalbenefits.

In addition, when using the manual technique, and because resultsgarnered from the manual process are not completely accurate, thesolution extraction is forced to depend on all kinds of environmentalconditions, such as precipitation, and temperature. Thus, neither thesampling conditions nor the results are precise.

There are also known suction lysimeters, as described, for example inU.S. Pat. No. 6,609,434. These lysimeters are inserted in a bore in thesoil to be sampled, vacuum is applied to suck soil solution into thelysimeter, and then the lysimeter is removed from the bore and thesample is analyzed.

Devices for analyzing collected soil solution samples are also wellknown. These generally sit in a laboratory to which the samples arebrought for analysis. There are also known various sensors for measuringvarious parameters, which are inserted directly into the soil to betested in the field.

Accordingly, there is a long felt need for a simple device for takingsoil solution samples under precisely controlled conditions fordetermination of fertigation parameters, and it would be very desirableif such device were substantially automatic.

SUMMARY OF THE INVENTION

The present invention provides a system and method for automaticallycollecting soil solution samples at predetermined intervals afterirrigation, and for a predetermined and controlled sampling time.

According to the present invention, there is provided a system forcollecting soil solution samples including a sampling device arranged tobe planted in soil to be monitored, the sampling device being coupled toa vacuum source, and a suction unit for automatically controllingpressure and time of operation of the vacuum source to provide suctionfor withdrawing solution from the soil through the sampling device, thesuction unit including a relief valve for abrupt release of vacuum atthe end of a pre-defined sampling period.

According to one embodiment of the invention, the sampling deviceincludes a porous extraction tube arranged to be planted in the soil,and a solution collecting bottle coupled to the extraction tube, thecollecting bottle being coupled to the vacuum source.

According to one embodiment of the invention, there is provided a systemfor collecting soil solution samples including a porous soil solutionextraction tube arranged to be implanted in soil, a solution collectingbottle coupled to the soil solution extraction tube by a vacuum tube,and a suction unit including a vacuum pump coupled to the solutioncollecting bottle for automatically controlling pressure and time ofoperation of the vacuum pump to provide suction for withdrawing solutionfrom the soil through the extraction tube and into the solutioncollecting bottle, the suction unit including a relief valve for abruptrelease of vacuum at the end of a pre-defined sampling period.

Further according to one embodiment, the system for taking soil solutionsamples includes a timer adapted to begin counting a pre-selected delaytime at the end of irrigation, the timer being coupled to a vacuum pumpcoupled to sampling devices inserted at desired locations in the soil,for automatically sucking solution from the soil adjacent the samplingdevices at the end of the delay time, and means for automaticallyreleasing the vacuum after a pre-selected sampling period.

According to a preferred embodiment of the invention, the system furtherincludes a plurality of testing sensors mountable in each collectingbottle, the sensors being coupled to an external location, such as acentral computer or a data log, for transferring electrical signalscorresponding to data collected by the sensors for analysis.

Further according to the present invention, there is provided a methodfor collecting soil solution samples including coupling a samplingdevice to a vacuum source, planting the sampling device in soil,automatically controlling pressure and time of operation of the vacuumsource to provide suction for withdrawing solution from the soil throughthe sampling device, and automatically stopping the vacuum source andabruptly releasing vacuum at the end of a pre-defined sampling period.

There is also provided, according to the invention, a method forcollecting soil solution samples including implanting at least one soilsolution extraction tube in soil, coupling a solution collecting bottleto the soil solution, extraction tube by a vacuum tube, coupling asuction unit including a vacuum pump to the solution collecting bottle,automatically controlling pressure and time of operation of the vacuumpump to provide suction for withdrawing solution from the soil throughthe extraction tube and into the solution collecting bottle, andautomatically stopping the vacuum pump and abruptly releasing vacuum atthe end of a pre-defined sampling period.

According to one embodiment, the step of automatically controllingincludes activating a timer at termination of irrigation to begincounting a pre-selected delay time, causing the timer to automaticallyinitiate vacuum to suck solution from soil adjacent the sampling tubesinto the sampling tubes at the end of the delay time, and automaticallystopping the vacuum and releasing the vacuum after a pre-selectedsampling period.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further understood and appreciated fromthe following detailed description taken in conjunction with thedrawings in which:

FIG. 1 is a schematic illustration of a single unit sampling station ina system for collecting soil solution samples constructed and operativein accordance with one embodiment of the invention;

FIG. 2 is a schematic illustration of a multiple unit sampling stationconstructed and operative in accordance with one embodiment of theinvention;

FIG. 3 is a schematic illustration of a field position scheme of asystem for collecting soil solution samples including an operatingcontrol unit and a plurality of sampling stations, according to oneembodiment of the invention;

FIG. 4 is a flow chart illustrating the method of operation of oneembodiment of the present invention;

FIG. 5 is a schematic illustration of a suction unit according to oneembodiment of the invention;

FIG. 6 is a schematic illustration of a system for collecting soilsolution samples constructed and operative in accordance with a furtherembodiment of the invention, including transferring the soil solutionsamples to a lab station; and

FIG. 7 is a schematic illustration of a solution collecting bottle foruse in a system for collecting soil solution samples constructed andoperative in accordance with yet another embodiment of the invention,including real-time analysis.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an automatic control system forcollecting soil solution samples that can closely control the extractionof soil solution on a real time basis. The system of the presentinvention controls the following main parameters in the solutionsampling process:

-   -   A. The length of time a farmer waits between the completion of        irrigation and initiation of sampling.    -   B. The length of time of extraction (sampling), or the volume of        extracted solution, for each sampling.    -   C. The vacuum power for extraction (which typically depends on        the soil type).

Each parameter is influenced by the type of soil, the system used inirrigation, and the condition of the soil before irrigation. While theparameters cannot be fixed absolutely, farmers will be able to approachoptimum conditions. Once the preferred parameters have been determined,the system may utilize substantially identical parameters for eachsampling. On the other hand, it will be appreciated that differentsampling locations may have different optimum parameters.

Referring now to FIG. 1, there is shown a schematic illustration of asingle unit sampling station 10 in a system for collecting soil solutionsamples constructed and operative in accordance with one embodiment ofthe invention. Sampling station 10 includes an extraction tube 12implanted in the soil in the location to be monitored. Sampling device12 can be, for example, a porous clay extraction tube, as known in theart. Extraction tube 12 is coupled by collecting vacuum tubing 14 to asolution collecting bottle 16. For purposes of the present invention, asolution collecting bottle refers to any container of suitable size andshape for collecting the desired volume of solution extracted from thesoil, and can be as small as a test tube. Solution collecting bottle 16,in turn, is coupled via control vacuum tubing 18 to a vacuum pump in asuction unit 20. Suction unit 20 may be controlled by a mechanical orelectronic timer or counter, as described below, thus creating anautomatic electromechanical suction system.

The timing of the start of sampling can be selected in a number of ways.At present, the following ways are contemplated. The timing of thesampling cycle can be selected by the farmer, based on professionalguidelines and suggestions. Activation of the pump or the timer can bemanual, but coordinated with the starting or finishing of irrigation ofthe monitored location. Alternatively, activation of the pump, or of thetimer can be automatically synchronized with the irrigation controller.Or sampling can begin automatically upon activation by a sensor in thesoil, for example, a soil moisture sensor, such as a tensiometer.

In the illustrated embodiment, suction unit 20 includes a timer (notshown). When the timer receives an activation signal, it begins to counta pre-set delay time to start the pump for sampling. Once the pump isstarted, the timer counts a pre-set sampling period and stops the pumpwhen the sampling period expires. Suction unit 20 also includes a manualoperating switch 24, for manual activation of sampling, without a delaytime. The sampling period is automatically ended by the timer after theexpiration of the pre-set sampling period, preferably by opening arelief valve to abruptly pressurize the tubing. This provides aprecisely defined and easily repeatable sampling time, which isvirtually impossible with conventional systems.

According to one embodiment of the invention, the timer is coupled to areset button 22. When a sampling cycle is finished, the timer waits in astandby mode to receive a reset signal. The reset signal initiates a newsampling cycle (so that every irrigation cycle does not automaticallyresult in sampling).

After reset, the timer waits for an activation signal, at which time thetimer is initialized and starts counting the sampling cycle. The resetbutton 22 may be pressed manually, or the timer may be reset by a remoteactivation means, such as a standard remote control, mobile phone, radiosignal, through the irrigation controller itself, or by any other means.Optionally, suction unit 20 may include an LED or other indicator, whichis activated when the system is working (i.e., when the system is undervacuum for taking soil solution samples), and possibly another indicatorto show when the timer has been reset, and the system is awaiting anactivation signal.

Suction unit 20 further includes a vacuum pump 28, preferably anelectric pump, or other source of vacuum. After the pre-set delay periodfrom activation of the timer has elapsed, or upon activation of themanual or automatic activation switch, vacuum pump 28 begins to reducepressure in the vacuum tubing 14 and 18, thereby drawing solution fromthe soil, through the solution extraction tube, into the soil solutioncollecting bottle by suction. Sampling continues for a pre-selectedperiod of time, as counted by the timer, and then the vacuum is releasedand vacuum pump is turned off. Preferably, a pressure relief valve 29 isprovided, which is opened after the sampling period expires, to releasethe vacuum abruptly.

FIG. 2 is a schematic illustration of a multiple unit sampling station30 in a system for collecting soil solution samples constructed andoperative in accordance with one embodiment of the invention. Thisembodiment is ideal for providing indications of the soil solutioncontents at various depths adjacent the roots of a plant. Samplingstation 30 includes three extraction tubes 32, 32′ and 32″ implanted atdifferent depths in the location to be monitored. It will be appreciatedthat, alternatively, a sampling station can include one, two, or moreextraction tubes, as desired for that particular location.

Each extraction tube 32, 32′, 32″ is coupled by collecting vacuum tubing31, 31′, 31″ to a solution collecting bottle 33, 33′, 33″ and viacontrol vacuum tubing to a suction unit 34, similar to that shown inFIG. 1. Suction unit 34 controls the sampling conditions, time andprocess for all three extraction tubes, and includes a manual resetswitch 35, a manual activation switch 36, a vacuum pump 37 and a vacuumrelief valve 41, substantially as described above. According to oneembodiment of the invention, all three samples are taken at the sametime, in parallel. Alternatively, sampling can be performed in thedifferent extraction tubes at different times (i.e., after differentdelays), for example, each depth at a different time. In addition,suction unit 34 preferably includes means permitting remote activationof the suction unit, i.e., for resetting and/or activating the timer.Alternatively, or in addition, a sensor, for sensing a condition of thesoil which determines the proper time to start the sampling period, maybe provided in the soil for automatic activation of the timer and thus,the pump. For example, a soil moisture sensor 45 may be providedadjacent each extraction tube 32 to sense the moisture level in the soilat the sampling location. Soil moisture sensor 45 can be coupled by wireor wireless communications, as known, to suction unit 34 for activatingthe timer by means of a remote activating input signal, when themoisture level reaches a pre-selected value. Should additionalinformation be desired, it is also possible to mount a camera (notshown), such as a video camera, at the sampling site, to supplyphotographs in real time, and to collect further data.

FIG. 5 is a diagram showing schematically the various components ofsuction unit 34. The dark lines indicate pressurized tubing, while thelighter lines indicate electrical wiring. The circuit is powered by avoltage source V, which can be the irrigation controller current,batteries in the soil sampling system control box, a solar panel, or anyother external power source. The suction unit 34 includes pump 37,powered by voltage source V and controlled by an electric timer switch52 and a relay switch 50, connected in series. Timer switch 52 may beinstalled either in the main irrigation controller box or, as shownhere, inside the suction unit of the soil sampling system.

Timer switch 52 can receive control signals from an activation button 36or a reset button 35. Activation button 36 can be actuated manually by afarmer by physically pressing the button. This closes timer switch 52and begins the counting of the delay period. Alternatively, activationbutton 36 may be actuated remotely, as described above, by means of aremote signal 39. If it is desired to cause the timer to immediatelyactivate the vacuum pump and begin counting the sampling period (withouta delay period), a different activation button 36′ or activation signal39′ may be provided.

According to one embodiment of the invention, a reset button 35 is alsoprovided, in order to prevent sampling from occurring after eachirrigation cycle. Reset button 35 can be actuated manually by a farmerby physically pressing the button. This closes timer switch 52 andcauses the timer to stop counting and await an activation signal.Alternatively, reset button 35 may be actuated remotely, as describedabove, by means of a remote signal 47.

It is a particular feature of the present invention that the pressure(vacuum) is carefully controlled at all times. Thus, suction unit 34includes a pressostat (vacuum switch) 43 or other pressure controller,which also controls pump 37. Pressure controller 43 maintains theworking pressure of the system, which changes according to theconditions at the sampling location. Thus, pump 37 is de-activated andre-activated, by pressure controller 43, depending upon the pressure inthe tubing. When pressure is, lower than the desired level of vacuum,the pressostat will open, thereby stopping operation of the pump. Itwill be appreciated that while the pump in stopped in this fashion, thepressure in the system gradually increases, since the relief valve isnot opened. As soon as the vacuum returns to the desired level, thepressostat closes, thus current is allowed to flow and re-activate thepump.

An external pressure gauge 38 may also be provided to indicate theactual pressure in the vacuum tubing and the system, thereby permittinga user to monitor the vacuum pressure in the tubing and, if necessary,manually operate the vacuum relief valve by means of a manual valveswitch 49. Pressostat 33 may be adjustable, thus providing for adjustingthe vacuum to a desired level. In addition, since the vacuum gauge ispreferably absolutely calibrated, it can be used for calibrating thesystem, as its readings can be relied upon while calibrating thepressostat.

One example of an apparatus 40 for collecting soil solution samplesaccording to the invention is shown schematically in FIG. 3, in a fieldposition scheme. Apparatus 40 includes an irrigation controller 42,which can be a conventional computerized controller, in an operationcontrol unit, which can be located in a central or easily accessiblelocation. Irrigation controller 42 is coupled to a plurality ofirrigation valves 44, each located in a different field or irrigationplot, by a hydraulic tube or electric cable, as known. In theillustrated embodiment, each irrigation valve is located in its ownirrigation plot 46.

Each irrigation plot 46 also includes a sampling station 48 according tothe present invention. The embodiment of FIG. 3 further includes aplurality of suction units 54, substantially as described above, locatedin the operation control unit, each associated with a different samplingstation. The operation control unit also houses a vacuum pump (notshown). Each of suction units 54 includes a timer 58 or other means ofactuating the relay switch to activate the vacuum pump. A reset switch59 is provided in the operation control unit between the irrigationcontroller 42 and each timer 58.

The timer receives an actuating signal, preferably an output signal fromthe irrigation controller or from the suction unit of each samplingstation. Once irrigation ends, the timer is automatically activated bythe signal coming from the irrigation controller and starts countingtime (begins its cycle).

The timer's active cycle includes:

-   -   A. Counting the delay period from the end of irrigation to the        start of the sampling.    -   B. Starting the system sampling (closing the relay switch, so        the vacuum pump begins to operate).    -   C. Counting the preset sampling period (at the end of which, the        relief valve is opened and the pump is turned off).

When the sampling process is terminated, the suction unit goes into astandby mode until the next reset signal is received by the timer.

According to one embodiment, the timer will not start working againuntil the “reset” button is pressed. According to this embodiment, thesampling system will not work if the switch is not manually reset to“on”, even though the irrigation controller will send the activationsignal to the timer. It will be appreciated that, after completion ofthe sampling cycle, the farmer must empty the solution collectingbottles, before activating the Reset button for the next cycle. It maynot be necessary to take soil solution samples after every fertigationcycle. Rather, the farmer decides, according to local conditions, whensampling is to occur, and sets the Reset button accordingly, only afterthose irrigation cycles which were selected for sampling. It willfurther be appreciated that setting of the Reset button can beaccomplished manually, or by means of a remote control system. As statedabove, the controller can receive a “reset” order from one of thefollowing options: standard remote control, mobile phone, SMS signal,through the irrigation controller itself, or by other means.

The following parameters are preferably controlled by the timer:

-   -   1. Delay Function—fixing the time delay from the termination of        irrigation to the activation of the vacuum pump (vacuum suction        in the soil).    -   2. Sampling Time function: fixing the time period for sampling        (while the vacuum pump is switched on). This function will be        fixed manually for a range of between one and 24 hours.

These parameters can be fixed either by a digital system—controlledthrough remote control—or manually. The length of time from the end ofirrigation to the start of the sampling can be manually adjustableaccording to environmental conditions, i.e., recent rain or drought,etc. Similarly, manual adjustment of sampling time is possible.Preferably, the timer itself is controlled by the “Reset” switch, mayalso initialize the counter. The timer will be equipped with a mini lampshowing whether it is in the “standby” or “active” position (preferably,an LED).

According to another embodiment, the sampling can be started by anoutput signal from a remote device operated by the farmer, or a soilmoisture sensor planted in the field adjacent the soil sampling station,or other external component of the system. Furthermore, the samplingperiod (i.e., the time until the relay switch is opened) can be fixed bythe volume of solution collected in the solution collecting bottle,rather than a fixed length of time. (It will be appreciated that therate of filling the solution collecting bottle can be an importantparameter concerning the state of the soil adjacent the extractiontube.) Immediate release of the vacuum at the end of the sampling periodhelps to achieve the maximum controlled conditions, which providesbetter over-all results, and is provided at the end of the samplingsession, which is pre-defined, as by length of time or quantity ofsolution collected.

It will be appreciated that the timing of the start of sampling need notbe identical for all the sampling stations. Thus, different timing canbe provided, for example, for sampling stations at different depths inthe field, or for sampling stations in different areas of the locationto be monitored, and can be triggered and counted in any of the waysmentioned above, or in any other fashion.

Operation of these embodiments of the system of the present invention isas follows, as illustrated schematically in FIG. 4. The cycle beginsupon termination of irrigation (block 60). For manual operation, afarmer waits a selected amount of time, and the presses the manualactivation button (block 62). The manual activation button serves toactivate the timer (block 82) without delay (i.e., delay is finished(block 84)) which activates the vacuum (block 64). Suction is nowprovided (block 66), thereby drawing solution from the soil, through theextraction tube and into the collecting bottle. The pressostatcontinuously determines whether the vacuum level is too high (block 65).If it is, the pressostat turns the pump off (block 67) until the vacuumlevel is correct, at which time, the vacuum pump is activated again(block 64). If the vacuum level is not too high, the suction continues(block 68) until the pre-selected suction time (sampling period) haspassed (block 70), or the pre-selected volume of collected solution hasbeen obtained, or the end of the sampling cycle has been reached, asdetermined by another pre-defined parameter, at which time the vacuum isreleased (block 71), thereby stopping the suction of solution into thecollecting bottles. The solutions from the collecting bottles arecollected by the farmer (block 72) and the cycle ends (block 74). Thecollected solutions are now taken to a lab for analysis of the varioussoil parameters in each sampling location.

For automatic operation with a timer, the cycle begins with reset of thetimer, which can be manual or automatic (block 76). Upon termination ofirrigation (block 60), the timer receives an activation signal (block78). The system determines whether the timer has been reset (block 80).If not, the cycle ends (block 74). If there has been reset, the timer isactivated (block 82) to begin the pre-selected time delay. Once the timedelay has finished (block 84), the timer activates the vacuum (block64), and the process continues as described above with regard to themanual procedure.

It is a particular feature of the invention that, when the pre-setsampling period has elapsed, timer 52 opens relay switch 50 to stopoperation of the pump and simultaneously actuates the relief valve 41for substantially instantaneous pressurization of the tubing system. Atthis time, the timer goes into the standby mode, until it receives areset signal.

One of the onerous tasks of the conventional soil solution samplingsystems is the transport of filled sampling bottles to a lab foranalysis or, at the very least, sending someone with a field test kit tothe site to analyze the solution samples. The lab analysis preferablydetermines the following parameters:

-   -   A. Soil solution salinity (e.c.).    -   B. Soil solution acidity (pH).    -   C. Concentration and availability of nitrogen, potassium and        phosphorus (NPK), or any other element required by the        particular plant.

The NPK are macro elements, which are essential to the plant and areconsumed in significant amounts during the growing period. The amountconsumed changes according to the growing conditions and the stage ofplant growth. Fine tuning of the quantities of each of the NPK elementsis very important to achieve the best growth. Analysis of the labresults will be the basis for the farmer in making final decisions aboutfertilizer, irrigation and other required treatment of the soil in eachsampling location. Preferably the amount of solution or liquid volumecollected in each sampling bottle over a given sampling time should alsobe measured and recorded, as this parameter can be an importantindicator of various characteristics of the soil at a given time.

According to the following embodiments of the invention, the sampletransport process, too, can be automated, so as to increase theconsistency of the sampling procedure and improve results.

Referring now to FIG. 6, there is shown a schematic illustration of asystem 100 for collecting soil solution samples constructed andoperative in accordance with a further embodiment of the invention. Thisembodiment does not require the farmer to transport solution collectingbottles to a lab, but rather includes means for automaticallytransferring the soil solution samples to a lab station. It will beappreciated, in this embodiment, the timer can be a part of acontroller, such as a pc computer, and the controller can be programmedto the different needs of the different sampling stations. Thecontroller would include a program for the timer for each station, orgroup of stations which can be simultaneously sampled. Alternatively,this control can be carried out by an irrigation controller, which mustswitch between several programs for the timer for different groups ofsampling stations where sampling can be conducted simultaneously (i.e.,requiring the same sampling parameters). Thus, the irrigation controllerwould control the timer to select pre-selected delay and samplingperiods, depending on which locations are being sampled, as well as thesequence between the groups.

System 100 includes a plurality of sampling stations 102, of which oneis illustrated, and a laboratory station 120. Sampling stations 102 eachinclude one or more extraction tubes 104 implanted in the soil in thelocation to be monitored. Each extraction tube 104 is coupled bycollecting vacuum tubing 106 to a solution collecting bottle 108. Eachsolution collecting bottle 108, in turn, is coupled via control vacuumtubing 110 to a solenoid valve 114 in a vacuum suction unit 112, ofwhich only a portion is illustrated. Solenoid valves 114 alternatelycouple vacuum tubing 110 to a vacuum pump (not shown) for providingsuction, or to the atmosphere, to release the vacuum. It will beappreciated that, in this embodiment, vacuum is provided substantiallyall the time, so that no activation signal or reset of the system isrequired. Rather, the timer can be part of a computerized controllerwhich controls the delay period (if any) and the sampling period.

Vacuum suction unit 112 is coupled or wired to a system suction unit,similar to that described above, which is not shown in the illustration.It will be appreciated that each solution collecting bottle 108 iscoupled to its own solenoid valve 114. Typically, each extraction tube104, even if there is more than one at a sampling station, is coupled toits own collecting bottle.

In the embodiment of FIG. 6, an additional tube 116 is provided fortransferring solution from solution collecting bottle 108, at the end ofeach sampling session, to the lab station 120. Lab station 120 alsoincludes a plurality of solenoid valves 122, each coupling one transfertube 116 to vacuum tubing 124 leading into an analysis container 126.Solenoid valves 122 have two states—either vacuum or closed. Theinterior of analysis container is connected by vacuum tubing 128 to avacuum pump (not shown) for providing suction to introduce, one afterthe other, solution samples from the various collecting bottles viavacuum tubing 116 and 124 into analysis container 126. A vacuum pipe 130with associated solenoid valve 132 is provided for emptying analysiscontainer 126, and a fresh water pipe 134 and associated solenoid valve136 is provided for rinsing or flushing analysis container 126 betweensolution samples.

A plurality of testing sensors 138 (here represented as a single block)are disposed in analysis container 126 for testing various soil solutionparameters, such as salinity, acidity, and concentration of N, P and K,as discussed above, and any other element or compound required by theplants in the location to be monitored, for example, calcium, magnesium,sodium, or even microelements. It will be appreciated that the sametests need not be performed on all the collecting bottles, but that thelaboratory station can be programmed to run different tests on samplesfrom different locations or depths, as desired. Preferably, a dataconnection 140 is provided to permit transfer of the results from thevarious testing sensors to a data log (not shown), and/or to a centralcomputer or other external location for on-line or off-line analysis ofthe test results. Data connection 140 can be any conventional dataconnection, including wired, wireless, and optical.

Operation of the system of the embodiment of FIG. 6 is as follows. Soilsampling is carried out in any of the ways discussed above withreference to FIGS. 1 to 5. The pressure is reduced in vacuum tubing 110by opening valve 114 in vacuum controller 112 to the vacuum source, andsuction of soil solution through extraction tube 104 begins. At thisstage, solenoid valve 122 is closed. Once the sampling has ended, thevacuum is released in solution collecting bottle 108, by openingsolenoid 114 to the atmosphere, and the analysis container's vacuum pumpis activated. Solenoid 122 for a first sampling station is opened, andsuction is applied via vacuum tubing 128, 124 and 116 to withdraw thesolution collected in solution collecting bottle 108 into analysiscontainer 126. At this time, valves 132 and 136 are closed, while valves142 and 144 are open.

The collected solution is analyzed by sensors 138, and the datatransferred to the data log. Now the analysis container is emptied.Valve 122 is closed, as are valves 136 and 144, valve 142 is opened tothe atmosphere, and valve 132 opens vacuum pipe 130 to suction theanalyzed solution out of container 126 for disposal. Once container 126is empty, valve 132 is closed and the procedure begins again with asolution sample from a different collecting bottle in the same or adifferent sampling station.

If desired, analysis container 126 can be rinsed between each sample.(Rinsing may not be necessary, as in cases where tests are repeatedfrequently when the solutions are very similar to each other.) This isaccomplished by opening valve 136 to permit the inflow of fresh waterthrough fresh water pipe 134 into container 126 to rinse the sensors andthe walls of the container. Valves 136 and 144 are then closed, cuttingoff the flow of fresh water, valve 142 is opened to the atmosphere, andvalve 132 is opened to provide vacuum to suction out the rinse water.

It will be appreciated that this embodiment will require that the timerperform additional functions to those described above with reference toFIGS. 1 to 5. First, the timer will be responsible for coordinatingoperation of the various solenoid valves, to control application andrelease of the vacuum, introduction of fresh water, and suction removalof solution and rinse water from the analysis container. In addition,the timer will be responsible for coordinating transfer of the collectedsolutions from the various collecting bottles in the appropriate orderand at the appropriate time. If desired, the timer can be part of acomputerized controller, which will be programmed to control all theseoperations.

It is a particular feature of the embodiment of FIG. 6 that the farmeris relieved of the need to manually transport dozens of collectingbottles to a lab at various times of the day in order to receive theresults of analysis of the collected solutions.

According to an alternative embodiment, illustrated schematically inFIG. 7, the system for collecting soil solution samples can includereal-time analysis in each solution collecting bottle, without the needfor a central lab at all. FIG. 7 shows a solution collecting bottle 150according to one embodiment of the invention. Solution collecting bottle150 includes collecting vacuum tubing 152 coupling the collecting bottleto a sampling device (not shown) implanted in the soil in the locationto be monitored. Solution collecting bottle. 150, in turn, is coupledvia control vacuum tubing 154 to a vacuum pump (not shown) for providingsuction to collect solution from the soil into collecting bottle 150, asdescribed above.

A plurality of testing sensors 156 are disposed in collecting bottle 150so as to be immersed in the soil solution. Thus, testing sensors 156 arearranged for testing, in real time, various soil solution parameters,such as salinity, acidity, and concentration of N, P and K, and others,such as Ca, Mg, Na, or microelements, as discussed above. Preferably, adata connection 158 is provided to permit transfer of the results fromthe various sensors to any external system, such as a data log, externallab, and so on. Data connection 158 can be any suitable type ofconnection. According to one embodiment of the invention, a solutionlevel sensor 160 is also provided inside collecting bottle 150. Solutionlevel sensor 160 can be coupled to the controller of the system (notshown) for providing a signal to indicate the end of the sampling timewhen a pre-set volume of solution has been collected. Thus, in thiscase, the solution level sensor would activate the relief valve to stopthe vacuum and stop collection of solution, instead of the timer.

A vacuum pipe 162 is provided for emptying collecting bottle 150 betweensampling times. If desired, a fresh water pipe and associated solenoidvalve can be provided for rinsing out the solution collecting bottle, asdescribed with reference to FIG. 6.

According to one embodiment of the invention, instead of sampling thesolution continuously over the sampling period, small samples arewithdrawn with a pause between them, without emptying the collectingbottle, so as to monitor the gradual change over the sampling time ofvarious selected parameters of the solution.

One advantage of the embodiments including real-time analysis, such asin FIGS. 6 and 7, is that a warning system can be provided to indicate asoil solution condition which is hazardous to the plant growth. In thiscase, a database can be provided including the permitted range of eachof the elements tested for. When the analyzed data indicates a quantityoutside of the permitted range, i.e., excess salinity or acidity, orlack of a crucial element or substance required for plant growth, awarning indication would be provided, audibly, visually, via a messageto a cell phone or to a central controller, or in any other fashionwhich would permit prompt investigation of the situation.

In all the embodiments of the invention, the results of the labanalysis, whether independent of the soil solution sample collectionsystem or part of the system, are provided to the farmer. Otherparameters exist, as well. Although they are more difficult to control,mainly in open fields, they are important enough for farmers to takeinto consideration when making their decisions. These include: day andnighttime outdoor temperatures, the length of daylight, relativehumidity, the amount of light and UV radiation (the light spectrum), CO₂concentration in the air, rainfall, the type and condition of the soil,the type of plant and the plants' stage of growth.

The farmers will evaluate all the information that has been collected,using data tables or graphic curves that show the changes over time foreach parameter. The lab analysis, together with information regardingthe preferred conditions for each plant at its stage of growth, will bethe basis for making short term and long term decisions aboutfertigation. The farmer can adjust, accordingly, the intervals betweenirrigation, the amount of water, fertilizer, and the NPK content aselements in the fertigating solution. He or she can also adjust thevarious sampling parameters, as required, such as the time intervalafter irrigation, the strength of the vacuum used for suction, theappropriate sampling time, etc.

While the invention has been described with respect to a limited numberof embodiments, it will be appreciated that many variations,modifications and other applications of the invention may be made. Itwill further be appreciated that the invention is not limited to whathas been described hereinabove merely by way of example. Rather, theinvention is limited solely by the claims which follow.

1. A system for collecting soil solution samples comprising: a samplingdevice arranged to be implanted in soil to be monitored, said samplingdevice being coupled to a vacuum source; and a suction unit forautomatically controlling pressure and time of operation of said vacuumsource to provide suction for withdrawing solution from the soil throughsaid sampling device, said suction unit including a relief valve forautomatic, abrupt release of vacuum at the end of a pre-defined samplingperiod.
 2. The system according to claim 1, wherein said sampling deviceis a soil solution extraction tube.
 3. The system according to claim 2,further comprising a solution collecting bottle coupled to said soilsolution extraction tube by a vacuum tube, wherein said suction unitincludes a vacuum pump coupled to said solution collecting bottle toprovide suction for withdrawing solution from the soil through saidsampling device and into said solution collecting bottle.
 4. The systemaccording to claim 1, wherein said suction unit further includes a timerfor automatically activating said vacuum pump, and for automaticallystopping said vacuum pump and opening said relief valve after apre-selected sampling period.
 5. The system according to claim 4,wherein said timer includes means for providing a pre-selected delayperiod after termination of irrigation before automatically activatingsaid vacuum pump.
 6. The system according to claim 1 wherein the suctionunit further comprises: a vacuum pump controlled by an electric timerswitch and a relay switch, connected in series; and a pressurecontroller, which also controls the vacuum pump.
 7. The system accordingto claim 6, further comprising reset means for resetting said timer.8-9. (canceled)
 10. The system according to claim 6, further comprisingmanual activation means for activating said timer.
 11. The systemaccording to claim 7, further comprising remote activation means foractivating said timer after reset.
 12. The system according to claim 1,further comprising a soil moisture sensor coupled to said suction unitfor automatically activating said timer to operate said vacuum pump whena pre-selected moisture level is reached in the soil to monitored.
 13. Asystem according to claim 1 comprising: at least two soil solutionextraction tubes arranged to be implanted in soil at different depths;and a solution collecting bottle coupled to each soil solutionextraction tube by a vacuum tube; wherein said suction unit includes avacuum pump coupled to each solution collecting bottle for automaticallycontrolling pressure and time of operation of said vacuum pump toprovide suction for withdrawing solution from the soil through each saidextraction tube and into said coupled solution collecting bottle, saidsuction unit including a relief valve for automatic, abrupt release ofvacuum in each said vacuum tube at the end of a pre-defined samplingperiod for that extraction tube.
 14. The system according to claim 3,further comprising: a plurality of testing sensors mounted in eachsolution collecting bottle, said sensors being coupled for communicationof sensed data to an external location.
 15. The system according toclaim 3, further comprising: a laboratory station selectably couplableto each solution collecting bottle for automatic transfer of solution insaid solution collecting bottle to said laboratory station for analysis.16. The system according to claim 15, wherein said laboratory stationincludes: a solution analysis container selectably couplable to eachsolution collecting bottle in sequence for transfer of said solutionfrom said collecting bottle to said analysis container; a vacuum suctionunit for selectably providing vacuum to each solution collecting bottlefor transfer of said solution; a plurality of testing sensors mounted insaid analysis container, said sensors being coupled for communication ofsensed data to an external location; and vacuum pipe for emptying saidsolution analysis container after testing by said testing sensors. 17.The system according to claim 16, further comprising a fresh water pipefor providing fresh water for rinsing said solution analysis containerafter emptying.
 18. The system according to claim 14, further comprisingmeans for analyzing said sensed data and providing an outputcorresponding thereto.
 19. The system according to claim 18, furthercomprising a warning system for providing an indication when said senseddata is outside a pre-selected range of data.
 20. A method forcollecting soil solution samples comprising: providing vacuum to createsuction for withdrawing solution from soil to be monitored;automatically controlling pressure and time of operation of said vacuum;and automatically stopping said suction and automatically, abruptlyreleasing the vacuum at the end of a pre-defined sampling period. 21.The method of claim 20, wherein said step of automatically controllingincludes: activating a timer for counting a time to automaticallyinitiate vacuum to suck solution from soil; and causing said timer toautomatically stop the vacuum and release the vacuum after apre-selected sampling period 22-27. (canceled)
 28. The method accordingto claim 20, further comprising automatically transferring solutionwithdrawn from the soil to a laboratory station for analysis. 29-33.(canceled)